Spatial configuration of anthropogenic land cover impacts on urban warming

Anthropogenic land cover types greatly influence the urban heat island (UHI) effects. This study examined effects of composition and spatial pattern of anthropogenic land cover features on land surface temperature (LST) in Phoenix, Arizona, USA, using a land cover map derived from high resolution satellite data and ASTER LST data. The spatial pattern of land cover features was measured by local Moran's I-a continuous spatial autocorrelation index, which can effectively describe dispersed or clustered patterns of land cover features. Our results showed that the composition and spatial pattern of buildings have minimal impacts on LST, while those of paved surfaces alter LST more drastically. The local Moran's I of paved surfaces have a stronger positive correlation with nighttime (r2 = 0.38) than daytime (r2 = 0.17) temperatures, suggesting that clustered paved surfaces create stronger warming effects at night. We further controlled for land cover compositions to minimize their effects on LST, and found that the magnitude of warming effects caused by clustered paved surfaces differed among landscapes of varying land cover compositions. Correlations between local Moran's I of paved surfaces and LST becomes stronger when paved surface fraction exceeds 50%. These results illustrated aggregate warming effects of clustered paved surfaces, and provide insights on UHI mitigation for land managers and urban planners.